Field of the Invention
This invention relates to unmanned aerial vehicles (UAVs), and in particular to multi-rotor UAVs.
Description of Related Art
Substantial prior art exists for multi-rotor helicopter designs. U.S. Pat. No. 2,529,033 (Linville), issued Nov. 7, 1950, U.S. Pat. No. 2,540,404 (John), issued Feb. 6, 1951, U.S. Pat. No. 2,623,711 (Pullen), issued Dec. 30, 1952, U.S. Pat. No. 2,646,130 (Udelman), issued Jul. 21, 1953, U.S. Patent Publication No. 2014/0032034 (Raptopoulos), published Jan. 30, 2014, and U.S. Design Pat. No. D710,452 (Barajas), issued Aug. 5, 2014, are just a few of the numerous U.S. patent that disclose various iterations on the multi-rotor theme.
In addition, multiple cross-flow fan propelled aircraft designs have been disclosed in U.S. Pat. No. 6,016,992 (Kolacny), issued Jan. 25, 2000, U.S. Pat. No. 6,527,229 (Peebles), issued Mar. 4, 2003, U.S. Pat. No. 7,641,144 (Kummer), issued Jan. 5, 2010, U.S. Pat. No. 8,579,573 (Kolacny), issued Nov. 12, 2013, and U.S. Patent Publication Nos. 2012/0111994 (Kummer), published May 10, 2012 and 2014/0048657 (Lin), published Feb. 20, 2014.
The prior art does not disclose hybrid multi-rotor helicopters utilizing a combination of axial fans for vertical thrust (i.e. hover capability) and one or more cross-flow fans for horizontal thrust (i.e. forward flight). As a result, prior art vehicles have limited forward flight speed and internal cargo volume.